[Tooling] skip anonymous namespaces when checking if typeLoc references a type decl from a different canonical namespace.

Summary:
[Tooling] skip anonymous namespaces when checking if typeLoc
references a type decl from a different canonical namespace.

Reviewers: bkramer

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D22808

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@276754 91177308-0d34-0410-b5e6-96231b3b80d8